Biomedical subjects
Publications and source records attributed to B Hingerty.
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Ultraviolet irradiation of 5-ethylorotate in aqueous medium led to formation of 5-ethylidenehydroorotate via a 1,3-hydrogen rearrangement from the ethylene group of the 5-substituent to the ring C6. The same product was also obtained by an alternate pathway via a hitherto unidentified intermediate. The structure of this unusual pyrimidine analogue, established in the solid state by X-ray diffraction, was shown with the aid of spectroscopic methods to be the same in solution, and some of its properties are described. Heating of 5-ethylidenehydroorotate in the solid state led by direct conversion to a mixture of the parent 5-ethylorotate and 5-ethyluracil. By contrast, ultraviolet irradiation in aqueous medium resulted in quantitative photochemical conversion of the photoproduct to 5-ethyluracil.
X-ray diffraction methods have been employed to establish the crystal structure of a new, unusual pyrimidine analogue, 5-ethylidenehydroorotate, obtained by a photochemical rearrangement of 5-ethylorotate. Crystals of the calcium salt of the title compound are monoclinic, space group Pc, cell constants a=14.631, b=10.038, c=19.168 A, beta=137.7 degrees, and contain four molecules, two cations and three water molecules per asymmetric unit. The structure was solved by direct methods and refined to R=5.2% on the basis of 2653 diffractometer measured data. The four independent molecules represent two pairs of enantiomers with slightly differing conformations linked together by an intricate system of hydrogen bonding and Ca2+-coordination (pentagonal bipyrimidal). The structure of the compound in aqueous medium, established by spectral methods, is the same as that in the crystal.